1. Field
The described technology relates generally to a thin film transistor and a manufacturing method thereof.
2. Description of Related Art
Generally, a thin film transistor includes a gate electrode, a semiconductor layer formed on the gate electrode and electrically insulated from the gate electrode by a gate insulating layer, and a source electrode and a drain electrode in contact with the semiconductor layer.
When the gate insulating layer of the thin film transistor is contaminated by a metal or a dopant, a leakage current or an off current (Ioff) can be generated. Although it would seem that a current would not flow since electrons do not move into the semiconductor layer when the thin film transistor is in the off state, a leakage current means that a current may flow in an off state, since electrons passing through the semiconductor layer exist.
To prevent the leakage current, an offset region where the gate electrode and the source electrode and drain electrode do not overlap may be formed in the semiconductor layer.
However, an on current (Ion) may be decreased by the offset region. Further, when the gate electrode overlaps the source electrode and the drain electrode such that the offset region may not be formed, an alignment error may be generated, and thereby the characteristics of the thin film transistor may be deteriorated.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.